SpringCloud商品服务调用方式之Ribbon

1、创建order_service项目

pom依赖

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

yml配置：

server:
  port: 8781

#指定注册中心地址
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

#服务的名称
spring:
  application:
    name: order-service

2、开发伪下单接口

@Service
public class ProductOrderServiceImpl implements ProductOrderService {


    @Autowired
    private RestTemplate restTemplate;

     // @Autowired， 启动时注入
     private LoadBalancerClient loadBalancer;

    @Override
    public ProductOrder save(int userId, int productId) {
         
      //从注册中心拉取product-service列表调用其url为api/v1/product/find 接口

        Map<String,Object> productMap = restTemplate.getForObject("http://product-service/api/v1/product/find?id="+productId, Map.class);

       //调用方式二
      // ServiceInstance instance = loadBalancer.choose("product-service");
       // String url = String.format("http://%s:%s/api/v1/product/find?id="+productId, instance.getHost(),instance.getPort());
      // RestTemplate restTemplate = new RestTemplate();
        // Map<String,Object> productMap = restTemplate.getForObject(url, Map.class);

       ProductOrder productOrder = new ProductOrder();
       productOrder.setCreateTime(new Date());
       productOrder.setUserId(userId);
        productOrder.setTradeNo(UUID.randomUUID().toString());
        productOrder.setProductName(productMap.get("name").toString());
      productOrder.setPrice(Integer.parseInt(productMap.get("price").toString()));

    return productOrder; } }

3、使用ribbon. (类似httpClient,URLConnection),客户端负载均衡

启动类增加注解

@SpringBootApplication
public class OrderServiceApplication {

public static void main(String[] args) {
SpringApplication.run(OrderServiceApplication.class, args);
}
//分析@LoadBalanced
//1）首先从注册中心获取provider的列表
//2）通过一定的策略选择其中一个节点
//3）再返回给restTemplate调用
//Ribbon自带负载均衡bean
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}

}

4、根据名称进行调用商品，获取商品详情

@RestController
@RequestMapping("api/v1/order")
public class OrderController {


@Autowired
private ProductOrderService productOrderService;


@RequestMapping("save")
public Object save(@RequestParam("user_id")int userId, @RequestParam("product_id") int productId){

return productOrderService.save(userId, productId);
}
}

启动 eureka, order-service, 以及多个 Product-service实例，会轮询从Product-service实例调用服务，实现负载均衡。

若想要自定义负载均衡，则可在order-service yml加入

#自定义负载均衡策略
product-service:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule